Conventionally, an image forming device, such as an ink-jet printer, which includes a head for discharging ink drops from the nozzles of the head, is known. Generally, one major problem that often arises in the image forming device and is detrimental to the performance of image formation with good quality is clogging of the nozzles of the head or dirt around the nozzles of the head. To avoid the problem, various preventive measures for preventing the occurrence of clogging, dirt, etc. in the image forming device have been proposed. For example, refer to the following related art documents.
Document 1: Japanese Patent No. 3480494 (Japanese Laid-Open Patent Publication No. 2003-001857)
Document 2: Japanese Laid-Open Patent Publication No. 03-247461
Document 3: Japanese Laid-Open Patent Publication No. 2003-001839
Document 4: Japanese Laid-Open Patent Publication No. 10-202904
Document 5: Japanese Laid-Open Patent Publication No. 57-061576
Document 6: Japanese Laid-Open Patent Publication No. 2001-205816
Document 7: Japanese Patent No. 3535885 (Japanese Laid-Open Patent Publication No. 07-096604)
Document 8: Japanese Laid-Open Patent Publication No. 2003-39689
Document 9: Japanese Laid-Open Patent Publication No. 10-151759
Document 10: Japanese Patent No. 3926094 (Japanese Laid-Open Patent Publication No. 2002-166562)
Document 11: Japanese Laid-Open Patent Publication No. 2001-232805
However, the preventive measures proposed by the related art documents have the difficulty respectively, which will be explained below, and it is desired to develop new preventive measures for preventing the occurrence of clogging, dirt, etc. in the image forming device.
Specifically, one of the preventive measures according to the related art documents (for example, Document 1 or Document 2) is to perform a discharge recovering operation which discharges ink drops from the nozzles at times other than the time of image formation, in order to prevent the occurrence of clogging of the nozzles. Another of the preventive measures according to the related art documents (for example, Document 2, Document 3 or Document 4) is to attract ink from the nozzles at times other than the time of image formation, in order to prevent the occurrence of clogging of the nozzles. In these cases, there is the difficulty in that a certain amount of ink is wasted.
One of the preventive measures according to the related art documents (for example, Document 5) is to drive the head to a degree that does not cause ink drops to be discharged from the nozzles, in order to prevent the occurrence of clogging of the nozzles. In this case, if the head is left unused for a long time in a power-down state of the ink-jet printer, the viscosity of the ink is increased due to drying and there is the difficulty that clogging of the nozzles will easily occur.
One of the preventive measures according to the related art documents (for example, Document 2, Document 3 or Document 4) is to attach a cap to the head at times other than the time of image formation. In this case, the preventive measure for preventing occurrence of dirt around the nozzles at the time of image formation is inadequate. If the cap becomes dirty over an extended period of time, the head will be stained by the dirt in the cap.
One of the preventive measures according to the related art documents (for example, Document 4, Document 6, Document 7 or Document 8) is to allow a blade of an elastic material to contact the nozzle surface of the head in order to remove the remaining ink which cause clogging of the nozzles or dirt in the nozzles. In this case, there is the difficulty in that, when the viscosity of the ink is increased due to drying, the removal of the remaining ink is not performed adequately.
One of the preventive measures according to the related art documents (for example, Document 9 or Document 10) is to apply a cleaning liquid (which dissolves the ink by itself) to the nozzle surface of the head so that the dirt adhering to the nozzle surface of the head is dissolved by the cleaning liquid. In this case, if the cleaning liquid is scattered, another contamination may arise due to the cleaning liquid. There is also the difficulty in that the cleaning performance will be lowered due to deterioration of the cleaning liquid over an extended period of time and the use of the cleaning liquid will raise the cost.
One of the preventive measures according to the related art is to immerse the head in a container which is covered with a cleaning liquid, in order to clean the nozzle surface of the head. In this case, there is the difficulty in that the cleaning performance will be lowered due to deterioration of the cleaning liquid over an extended period of time. There is also the difficulty in that the use of the cleaning liquid will raise the cost. Moreover, the preventive measures of this type will require the container with a size in which the head can be immersed and the additional device for driving the head so that the head is immersed in the container. This will enlarge the image forming device in size.